Caption: Lew Kowarski (1907-1979), French nuclear physicist and engineer, inspecting equipment. Kowarski was part of the team that, in 1939, performed the experiments that established the possibility of nuclear chain reactions and therefore nuclear energy production. During 1945 Kowarski supervised the construction of Canada'a first nuclear reactor at the Chalk River Laboratories. He returned to France and supervised the construction of the first two French nuclear reactors in 1948 and 1952.